It's not perfect, but it's a very strong and useful signal.
Never in my life have I seen something with 98% and thought, well that was a crap movie.
And never in my life have I seen something with 35% and thought, that was amazing!
It's more in the 75-90% range where you have to consider the "dimensionality" of the thing, like whether it's a genre you like, or which individual reviewers match your tastes more precisely.
